<template>
	<div class="s-canvas">
		<canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
	</div>
</template>
<script>
	export default {
		name: 'Identify',
		props: {
			identifyCode: {
				type: String,
				default: '1234'
			},
			fontSizeMin: {
				type: Number,
				default: 28
			},
			fontSizeMax: {
				type: Number,
				default: 40
			},
			backgroundColorMin: {
				type: Number,
				default: 180
			},
			backgroundColorMax: {
				type: Number,
				default: 240
			},
			colorMin: {
				type: Number,
				default: 50
			},
			colorMax: {
				type: Number,
				default: 160
			},
			lineColorMin: {
				type: Number,
				default: 40
			},
			lineColorMax: {
				type: Number,
				default: 180
			},
			dotColorMin: {
				type: Number,
				default: 0
			},
			dotColorMax: {
				type: Number,
				default: 255
			},
			contentWidth: {
				type: Number,
				default: 112
			},
			contentHeight: {
				type: Number,
				default: 40
			}
		},
		methods: {
			// 生成一个随机数
			randomNum(min, max) {
				return Math.floor(Math.random() * (max - min) + min)
			},
			// 生成一个随机的颜色
			randomColor(min, max) {
				var r = this.randomNum(min, max)
				var g = this.randomNum(min, max)
				var b = this.randomNum(min, max)
				return 'rgb(' + r + ',' + g + ',' + b + ')'
			},
			drawPic() {
				var canvas = document.getElementById('s-canvas')
				var ctx = canvas.getContext('2d')
				ctx.textBaseline = 'bottom'
				// 绘制背景
				ctx.fillStyle = this.randomColor(
					this.backgroundColorMin,
					this.backgroundColorMax
				)
				ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
				// 绘制文字
				for (let i = 0; i < this.identifyCode.length; i++) {
					this.drawText(ctx, this.identifyCode[i], i)
				}
				this.drawLine(ctx)
				this.drawDot(ctx)
			},
			drawText(ctx, txt, i) {
				ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
				ctx.font =
					this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
				var x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
				var y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
				var deg = this.randomNum(-30, 30)
				// 修改坐标原点和旋转角度
				ctx.translate(x, y)
				ctx.rotate(deg * Math.PI / 270)
				ctx.fillText(txt, 0, 0)
				// 恢复坐标原点和旋转角度
				ctx.rotate(-deg * Math.PI / 270)
				ctx.translate(-x, -y)
			},
			drawLine(ctx) {
				// 绘制干扰线
				for (let i = 0; i < 2; i++) {
					ctx.strokeStyle = this.randomColor(
						this.lineColorMin,
						this.lineColorMax
					)
					ctx.beginPath()
					ctx.moveTo(
						this.randomNum(0, this.contentWidth),
						this.randomNum(0, this.contentHeight)
					)
					ctx.lineTo(
						this.randomNum(0, this.contentWidth),
						this.randomNum(0, this.contentHeight)
					)
					ctx.stroke()
				}
			},
			drawDot(ctx) {
				// 绘制干扰点
				for (let i = 0; i < 20; i++) {
					ctx.fillStyle = this.randomColor(0, 255)
					ctx.beginPath()
					ctx.arc(
						this.randomNum(0, this.contentWidth),
						this.randomNum(0, this.contentHeight),
						1,
						0,
						2 * Math.PI
					)
					ctx.fill()
				}
			}
		},
		watch: {
			identifyCode() {
				this.drawPic()
			}
		},
		mounted() {
			this.drawPic()
		}
	}
</script>
<style scoped>
	.s-canvas {
		height: 38px;
	}

	.s-canvas canvas {
		margin-top: 1px;
		margin-left: 8px;
	}
</style>